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Old Nov 3rd 2011, 06:51 PM   #1
cmc124
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Exclamation Hess' Law and Heat of Formation of MgSo4

I have never taken anything like this before and I am very confused on how to even begin. Using the loggerpro and the calorimeter I need to determine the heat of formation for Mg and MgSO4.

Here are the equations for Mg:
Initial y=-0.0001321x+20.3
Final y=-0.0007852x+30.69

I know the mass of Mg is 0.5 g, 200 mL of H2SO4, Density of H2SO4 is 1.1060
I need to know the initial and final temperature, q, and the heat of formation in kJ/Mol

...and MgSO4:
Initial y=-0.002809x+20.67
Final y=0.007441x+34.18

I know the mass of MgSO4 is 20.0427 g, 200 mL of H20
I need to know the initial and final temperature, q, and the heat of formation in kJ/Mol

THANK YOU SO MUCH!! I REALLY NEEDED YOUR HELP!
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Old Nov 4th 2011, 01:22 AM   #2
Unknown008
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I'm not acquainted with that loggerpro, but the initial and final equations you got are give the temperature right?

Take the constant in the equations for Mg. The initial constant is 20.3 and the final constant is 30.69. Those are the initial and final temperatures of the reaction respectively!

Same for the other one. And to get Q, you simply need to use the formula:

Q = mcT

In the first case, you should get: Q = (200*1.1060)(2.3)(30.69-20.3)

2.3 is the specific heat capacity of water. If you are asked to use another value, do use the given value.

So the same with the other reaction.

Then you will need to draw the Hess' Cycle and put the relevant information to get the heat of formation of MgSO4.
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enthalpy, heat of formation, hess' law, mgso4



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